"Clear the Cache": Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now" "Remove the Cookies" from sites that cause problems: Tools > Options > Privacy > Cookies: "Show Cookies" Start Firefox in [[Safe Mode]] to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). See [[Troubleshooting extensions and themes]] and [[Troubleshooting plugins]] If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears. You can use "Disable all add-ons" on the [[Safe mode]] start window to disable all extensions. You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit") ---- Do a malware check with a few malware scan programs. You need to use all programs because each detects different malware. Make sure that you update each program to get the latest version of the database. http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware http://www.superantispyware.com/ - SuperAntispyware http://www.safer-networking.org/en/index.html - Spybot Search & Destroy http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page .......... See also "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked and [[Searches are redirected to another site]]